The present invention relates to lawn mowers and in particular to cylinder cutting blades for lawn mowers.
The use of cylinder cutting blades is well known in the art of lawn mowers. Cylinder cutting blades comprise a plurality of cutting bars mounted on a frame which spiral around, in a helical fashion, the longitudinal axis of the cylinder cutting blade. The radial distance of the outer edge of the cutting bars from the longitudinal axis remains constant along the length of the cutting bars.
The cylinder cutting blade is mounted in the front of a lawn mower and rotated by a motor about its longitudinal axis. A stationary shear blade is located in close proximity to the path swept out by the outer edge of the rotating cutting bars so that any vegetation such as grass is sheared by the action of the rotating cutting bars shearing the vegetation against the shear blade. The helical design of the cutting bars ensure that a smooth shearing action takes place.
Traditional designs of cylinder cutting blade have metal cutting bars which are welded onto a metal frame. This results in a structure which is complicated and expensive to make.
GB 2,116,413 discloses a cylinder cutting blade which comprises a blade holder upon which are mounted disposable plastic blades. Such a construction, however, is complicated.
According to the first aspect of the present invention, there is provided a cylinder cutting blade for a lawn mower characterized in that it comprises at least two modular cylinder cutting blade sections which are rotationally connected together in succession in such a manner that rotation of one modular cylinder cutting blade section results in rotation of the other modular cylinder cutting blade section.
By manufacturing, the cylinder cutting blade in this manner, it provides a simple and cheap construction. Furthermore, it allows cutting cylinders of different lengths to be manufactured from one design of modular cylinder cutting blade section. The length of the blade is increased by increasing the number of modular cylinder cutting blade sections used.
It will be appreciated by a person skilled in the art that this invention can be utilized with any design of cylinder blade for a lawn mower. Each modular cylinder cutting blade section is effectively a short cylinder cutting blade which can be connected in series to an adjacent one to make a longer cutting blade.
The cylinder cutting blade can be constructed from at least two modular cylinder cutting blade sections, each modular cylinder cutting blade section having a longitudinal axis and a locking mechanism wherein the modular cylinder cutting blade sections are mounted in succession so that their axes are substantially co-axial and the locking mechanism of each modular cylinder cutting blade section interacts with the locking mechanism of adjacent modular cylinder cutting blade sections to rotationally lock that modular cylinder cutting blade section to the adjacent modular cylinder cutting blade sections so that rotation of one modular cylinder cutting blade section results in rotation of the adjacent modular cylinder cutting blade sections.
The cylinder cutting blade preferably comprises a longitudinal axis, a plurality of cutting bars which spiral around the longitudinal axis, and a frame to hold the cutting bars in their respective positions characterized in that the cylinder cutting blade is constructed from at least two modular cylinder cutting blade sections. Each modular cylinder cutting blade section comprises a longitudinal axis, a plurality of cutting bars which spiral around the longitudinal axis, a frame to hold the cutting bars in their respective positions, and a locking mechanism. The modular cylinder cutting blade sections are mounted in succession so that their axes are substantially co-axial. The locking mechanism of each modular cylinder cutting blade section interacts with the locking mechanism of adjacent modular cylinder cutting blade sections to rotatably lock the modular cylinder cutting blade section to the adjacent modular cylinder cutting blade sections. Therefore the rotation of the modular cylinder cutting blade section results in rotation of adjacent modular cylinder cutting blade sections.
According to the second aspect of the present invention, there is provided a lawn mower having a cylinder cutting blade characterized in that it comprises at least two modular cylinder cutting blade sections which are rotationally connected together in succession in such a manner that rotation of one modular cylinder cutting blade section results in rotation of the other modular cylinder cutting blade section to form the cylinder cutting blade.
According to the third aspect of the present invention, there is provided a modular cylinder cutting blade section characterized in that it is capable of connecting to at least one other modular cylinder cutting blade section in succession to form a longitudinal cylinder cutting blade so that rotation of the modular cylinder cutting blade section results in rotation of the other modular cylinder cutting blade section.